If you unlock bootloader without saving DRM-keys and TA, are they lost forever? (cannot get them back by flashing something, or by any means?) islosing DRM-keys and TA preventing me from installing Sailfish? (I understood features that require them aren't going to be ported by jolla anyway?) Or is backing them up only for if you want to return to Android stock ROM? Thanks.

If you unlock your bootloader you lost your DRM keys forever, the purpose of backup the DRM keys, is when you relock de bootloader and restore your DRM keys, you let your phone as it was never touched, after flashing stock rom